This invention relates to fifth wheel hitches and particularly to a low lube fifth wheel hitch assembly.
A common hitch for hauling large trailers is the well-known fifth wheel hitch which has a large bifurcated bearing plate that receives a kingpin and locks it in place with one or more jaws. The kingpin is mounted on a trailer which also has a bearing plate which rests upon and pivots on the hitch upper surface, to enable articulation between the trailer and its towing tractor. This pivotal action is typically aided by a layer of grease on the hitch surface. Because this grease is not only messy but also tends to retain dirt and dust which cause wear, it is undesirable.
Various attempts have been made in the past to provide a lubricious surface layer for the hitch without the extensive amount of grease normally required. These efforts are believed to be largely set forth or represented by U.S. Pat. Nos. 5,263,856 to Huehn et al; 3,174,812 to Widmer; 3,704,924 to Lowry; 3,275,390 to Franks; 5,066,035 to Athans et al; 3,924,909 to Kent et al; 4,121,853 to McKay; 4,169,635 to Szalay et al; 4,457,531 to Hunger; 4,542,912 to St. Louis; 4,752,081 to Reeners et al; and 4,805,926 to Mamery. Many of these would require total redesign of the hitch. Others involve fastening devices undesirably exposed on the top of the lubricious material. Some have the lubricious layer rather permanently mounted to the hitch so that replacement of a worn product is extremely difficult and costly. Structures such as in U.S. Pat. No. 3,174,812 require special cavities in the fifth wheel, and only provide a small bearing surface area considered inadequate. As a consequence of these and related shortcomings, fifth wheel hitches in use still basically comprise the well-known grease coated metal plate.